Method for processing of sewage sludge using pyrolysis to eliminate PFAS and other undesirable materials

Abstract

A system and method for processing sewage sludge using pyrolysis to eliminate and/or significantly reduce organic chemical compounds, including plastics, and to produce a biochar product that is safe for beneficial uses is provided. The system and method can utilize pyrolysis to treat sewage sludge which dramatically reduces or eliminates regulated and unregulated synthetic organic chemical compounds in the resultant biochar.

What is claimed is: 
     
       1. A method of treating a sewage sludge to produce a biochar product, the method comprising: subjecting the sewage sludge to pyrolysis at a temperature of at least 400 degrees C. for a minimum of 15 minutes and subjecting air emissions from the pyrolysis to carbon filtration treatment, whereby a biochar product is produced that is essentially free of PFAS,
 wherein the sewage sludge has at least 70% total solids content, 
 and wherein the pyrolysis is slow pyrolysis performed using indirect heating in the form of conduction at a heat transfer reaction rate of 100° C./min or lower using a continuous processing mechanism comprising a screw or a conveyance that allows the reaction process to continue uninterrupted while continuously feeding sewage sludge and simultaneously removing biochar, 
 and wherein there is no addition of catalysts or inert gases to the sewage sludge. 
 
     
     
       2. The method of  claim 1 , wherein the pyrolysis is conducted at a temperature of at least 580 degrees C. 
     
     
       3. The method of  claim 1 , wherein the sewage sludge to be pyrolyzed has at least 90% total solids content. 
     
     
       4. The method of  claim 1 , wherein the pyrolysis is conducted at a temperature of at least 580 degrees C. and the sewage sludge is pyrolyzed for a minimum of 30 minutes. 
     
     
       5. The method of  claim 1 , wherein the biochar product is essentially free of plastics. 
     
     
       6. A method of treating a sewage sludge to produce a biochar product, the method comprising: subjecting the sewage sludge to pyrolysis at a temperature of at least 400 degrees C. for a minimum of 15 minutes and absorbing PFAS from air emissions from the pyrolysis, whereby a biochar product is produced that is essentially free of PFAS,
 wherein the sewage sludge has at least 70% total solids content, 
 and wherein the pyrolysis is slow pyrolysis performed using indirect heating in the form of conduction at a heat transfer reaction rate of 100° C./min or lower using a continuous processing mechanism comprising a screw or a conveyance that allows the reaction process to continue uninterrupted while continuously feeding sewage sludge and simultaneously removing biochar, 
 and wherein there is no addition of catalysts or inert gases to the sewage sludge. 
 
     
     
       7. The method of  claim 6 , wherein the pyrolysis is conducted at a temperature of at least 580 degrees C. 
     
     
       8. The method of  claim 6 , wherein the sewage sludge to be pyrolyzed has at least 90% total solids content. 
     
     
       9. The method of  claim 6 , wherein the pyrolysis is conducted at a temperature of at least 580 degrees C. and the sewage sludge is pyrolyzed for a minimum of 30 minutes. 
     
     
       10. The method of  claim 6 , wherein the biochar product is essentially free of plastics. 
     
     
       11. A method of treating a sewage sludge to produce a biochar product, the method comprising: subjecting the sewage sludge to pyrolysis at a temperature of at least 400 degrees C. for a minimum of 15 minutes and filtering PFAS from air emissions from the pyrolysis, whereby a biochar product is produced that is essentially free of PFAS,
 wherein the sewage sludge has at least 70% total solids content, 
 and wherein the pyrolysis is slow pyrolysis performed using indirect heating in the form of conduction at a heat transfer reaction rate of 100° C./min or lower using a continuous processing mechanism comprising a screw or a conveyance that allows the reaction process to continue uninterrupted while continuously feeding sewage sludge and simultaneously removing biochar, 
 and wherein there is no addition of catalysts or inert gases to the sewage sludge. 
 
     
     
       12. The method of  claim 11 , wherein the pyrolysis is conducted at a temperature of at least 580 degrees C. 
     
     
       13. The method of  claim 11 , wherein the sewage sludge to be pyrolyzed has at least 90% total solids content. 
     
     
       14. The method of  claim 11 , wherein the pyrolysis is conducted at a temperature of at least 580 degrees C. and the sewage sludge is pyrolyzed for a minimum of 30 minutes. 
     
     
       15. The method of  claim 11 , wherein the biochar product is essentially free of plastics.